The broad aim of this study is to begin establishing an effective treatment for individuals who engage in non- suicidal self-injury (NSSI), as there are currently no evidence-based psychological interventions that directly target this transdiagnostic, maladaptive behavior (1). Epidemiological studies suggest that NSSI occurs in 19 to 25% of adult clinical samples (8), and is present across a range of Axis I and Axis II disorders (3, 15, 16). Extant treatments that have demonstrated initial promise in reducing NSSI incorporate a multitude of skills embedded in complex multi-component treatment programs (e.g., 26, 52, 63); thus, the treatment component(s) responsible for improvements in NSSI are not readily apparent. A growing body of research emphasizes the importance of emotion dysregulation in NSSI (e.g., 27, 28, 36). Emotion-focused psychological procedures, particularly that aim to foster greater emotional awareness and increase engagement in cognitive reappraisal strategies, may be critical in effective NSSI treatment (e.g., 34, 60, 65). The specific goals of te research study proposed for this fellowship are to investigate the effects of two specific emotion-focused treatment elements on parameters of NSSI while simultaneously providing invaluable training in research design and execution, use of ecological momentary assessment (EMA) methods, exploration of transdiagnostic psychopathological processes, and treatment development research. Participants will be ten individuals (N=10) who meet proposed DSM-5 criteria for NSSI disorder (9) and report engaging in NSSI to reduce or escape from negative emotions. The investigator will adapt two core modules of the Unified Protocol Transdiagnostic Treatment of Emotional Disorders (UP; 70) with the aim of reducing participants' non-suicidal self-injurious thoughts and behaviors (SITBs; 2). Each treatment module will consist of four 50-minute individual weekly sessions of emotion awareness training or cognitive reappraisal. The study will use a counterbalanced, combined-series (multiple baseline and phase change) design, which will allow for both between-subjects comparison and clients to serve as their own control (i.e., within-subjects comparison). Phase change will be determined idiosyncratically based on each participant's changes in frequency of non- suicidal SITBs. This single-case experimental design methodology offers the opportunity to flexibly tailor interventions to the individual as needed (115), and is recommended in research of harmful behaviors due to ending on a treatment phase, which can be extended to allow for good clinical care (71). The frequency and characteristics of non-suicidal SITBs will be monitored continuously with EMA on a smart-phone. Coursework, training, and mentorship germane to the proposed research will support the applicant's long-term goal to become an independent scientist-practitioner in this key field of mental health.